1. Field of the Invention
The present invention relates to a paper feeding apparatus, and more particularly to a paper feeding apparatus for use in, for instance, a printer having a paper processing section (printing section) for effecting printing on paper, and a facsimile apparatus and a copying apparatus having a paper processing section (reading section) for reading data on paper.
2. Description of the Related Art
A paper feeding apparatus adopted in a printer having a printing section as a paper processing section is disclosed in JP-A-4-75842U. In this paper feeding apparatus, the position of a paper guide for restricting the position of setting cassette paper is adapted to be changed in a multiplicity of stages. Further, Japanese Patent Utility Model Publication No. Hei 1-166550 discloses a paper feeding mechanism that is capable of restricting the position of setting recording paper (paper) in a longitudinal direction and a transverse direction.
As can be seen in these publications, in a paper feeding apparatus used in a printer, for example, the position of the paper guide is adjusted in correspondence with the paper size so as to prevent the paper from skewing. A similar operation is effected in a paper feeding apparatus used in a facsimile apparatus and a copying apparatus.
Among the conventional paper feeding apparatuses, an apparatus having a fixed-side paper guide and a movable-side paper guide capable of sliding in a direction of moving toward or away from the fixed-side paper guide is so arranged that the paper is set by being clamped by the fixed-side paper. guide and the movable-side paper guide so as to prevent the paper being fed to the paper processing section (the aforementioned printing section or reading section) from becoming offset from a proper position or skewing. In this paper feeding apparatus, the fixed-side paper guide and the movable-side paper guide which clamp the paper demonstrate the effect of preventing the positional offset of the paper from the proper position. or the skewing of the paper during feeding. In addition, the fixed-side paper guide serves to set the paper setting position at the proper position as the fixed-side paper guide is caused to abut against one lateral end of the paper during paper setting.
In such a paper feeding apparatus, when the paper is set, after an operator places the paper on a paper supporting surface with one lateral end of the paper abutting against the fixed-side paper guide, the operator forcibly slides the movable-side member in a direction in which the movable-side member approaches the fixed-side member, thereby moving the movable-side member to an appropriate position corresponding to the paper size.
However, it is troublesome to effect the operation of sliding the movable-side paper guide in correspondence with the paper size each time the paper is set.
In addition, there are cases where the movable-side paper guide moves due to some cause and is separated from the paper during the feeding of paper to the printing section of the printer or the reading section of the copying apparatus, and if the condition in which the movable-side paper guide is separated from the paper is left as it is, the paper is likely to skew. Accordingly, when it is found out that the movable-side paper guide has separated from the paper, the movable-side paper guide is slid again to be moved to the appropriate position, but that operation has been troublesome.
The invention has been devised under the above-described circumstances, and its object is to provide a paper feeding apparatus in which even if the position of the paper placed on the paper supporting surface is positionally offset from a proper position, the position of the paper can be corrected to a proper position.
Another object of the invention is to provide a paper feeding apparatus in which the movable-side paper guide automatically returns to an appropriate position even if the movable-side paper guide has been separated from the paper due to some cause during feeding.
The paper feeding apparatus in accordance with the invention comprises: paper-position correcting means for pressing and urging at least one of one lateral end and the other end of paper placed on a paper supporting surface, thereby moving the paper to a proper position on the paper supporting surface so as to position the paper at the proper position. For this reason, when the position of the paper placed on the paper supporting surface has become-positionally offset from a proper. position, the paper-position correcting means presses and urges one or both of the one lateral end and the other lateral end of the paper, thereby moving the paper to the proper position so as to position the paper at the proper position.
In the invention, the power for feeding the paper to the paper processing section is utilized as the force for pressing and urging the one lateral end or the other lateral end of the paper. For this reason, there is an advantage in that it is unnecessary to separately provide a driving source for operating the paper-position correcting means and a power transmitting passage. The xe2x80x9cpaper processing sectionxe2x80x9d corresponds to a printing section of a printer, a reading section of a facsimile apparatus or a copying apparatus, or the like.
In the paper feeding apparatus of the invention, preferably, there are provided a fixed-side paper guide for positioning the paper at the proper position on the paper supporting surface as the one lateral end of the paper is caused to abut against the fixed-side paper guide, and a movable-side paper guide opposed to the fixed-side paper guide and disposed in such a manner as to be capable of moving toward or away from the fixed-side paper guide, the paper-position correcting means including the movable-side paper guide, the movable-side paper guide being urged in a direction of approaching the fixed-side paper guide so as to press and urge the other lateral end of the paper.
The paper feeding apparatus may be arranged such that the movable-side paper guide is slidably attached to a guide shaft which is rotatably provided along the paper supporting surface, and power for feeding the paper to the paper processing section is transmitted to the guide shaft to cause the guide shaft to rotate. In this case, it is possible to adopt an arrangement in which the paper-position correcting means is formed by the movable-side paper guide, a helical groove provided in the guide shaft, an engaging member engaged with the helical groove to translate rotary motion of the guide shaft to sliding motion of the movable-side paper guide, and a disengaging mechanism for canceling a state of engagement between the engaging member and the helical groove when the paper is clamped by the fixed-side paper guide and the movable-side paper guide and a force for pressing the other lateral end of the paper has reached a fixed magnitude or more.
In accordance with the paper feeding apparatus constructed as described above, when the power for feeding the paper to the paper processing section is transmitted to the guide shaft to rotate the guide shaft, the rotary motion of the guide shaft is translated to the sliding motion of the movable-side paper guide, so that the movable-side paper guide presses and urges the other lateral end of the paper to cause the one lateral end of the paper to abut against the fixed-side paper guide. When the paper is thus clamped by the fixed-side paper guide and the movable-side paper guide and its position is corrected to the proper position, the force for pushing one lateral end of-the paper by the movable-side paper guide increases and assumes a magnitude exceeding a fixed level, so that the disengaging mechanism cancels the state of engagement between the engaging member and the helical groove, thereby keeping the movable-side paper guide at the proper position corresponding to the paper size.
In the paper feeding apparatus in accordance with the invention, preferably, there is provided paper feeding means for feeding the paper to the paper processing section by imparting a feeding force to the paper placed on the paper supporting surface, an input rotating shaft of the paper feeding means being formed by the guide shaft. If this arrangement is adopted, since the guide shaft is jointly used as the input rotating shaft of the paper feeding means, it becomes unnecessary to use the guide shaft separately from the input rotating shaft, so that an increase in the number of component parts can be suppressed.
The engaging member is preferably formed of a synthetic resin integrally with the movable-side paper guide. If this arrangement is adopted, since it is unnecessary to form the engaging member as a separate component, an increase in the number of component parts can be suppressed.
Preferably, a tubular portion fitted slidably to the guide shaft is provided on the movable-side paper guide, and the engaging member is formed by a pawl provided at a distal end of a resilient movable piece which is formed by forming. split grooves at two positions in a tubular wall of the tubular portion and is flexurally deformable in inward and outward directions of the tubular portion. If this arrangement is adopted, a guide member necessary for slidingly moving the movable-side paper guide is jointly used by the guide shaft. In addition, since the movable piece of the engaging member is formed by one portion of the tubular wall of the tubular portion, it becomes unnecessary to provide the tubular portion and the engaging member at separate positions.
Preferably, the disengaging mechanism has an inclined surface provided on the pawl, and is so arranged that when the paper is clamped by the fixed-side paper guide and the movable-side paper guide and the force for pressing the other lateral end of the paper by the movable-side paper guide has reached the fixed magnitude or more, a helical projection forming the helical groove presses the inclined surface to cause the pawl to be lifted up from the helical groove and to be disengaged therefrom. According to this arrangement, it is unnecessary to form a complicated mechanism as the disengaging mechanism, and the disengaging mechanism can be constructed simply, so that the paper feeding apparatus can be provided at the low costs.
In addition, a grip for causing the pawl to be disengaged from the helical groove by deflecting the movable piece-against its resiliency is-preferably provided in such a manner as to be connected to the movable piece. If this arrangement is adopted, in a case where there has arisen a need to move the movable-side paper guide horizontally by a large distance, the movable-side paper guide can be slidingly moved by simply disengaging the pawl from the helical groove by operating the grip without rotating the guide shaft.